1. Field of the Invention
Aspects of the present invention relate to an organic electrolytic solution and a lithium battery employing the same, and more particularly, to an organic electrolytic solution including a radical initiator and a polymerizable monomer and a lithium battery employing the same.
2. Description of the Related Art
Batteries are used as power sources for portable electronic devices, such as video cameras, mobile phones, laptop computers, and the like. In particular, rechargeable lithium batteries have 3 times the energy density per unit weight as Pb batteries, Ni—Cd batteries, Ni—H batteries, and Ni—Zn batteries, and the rechargeable lithium batteries can be quickly charged and recharged. Lithium batteries operate at high operating voltages so that an aqueous electrolytic solution cannot be used and the aqueous electrolytic solution vigorously reacts with lithium. In general, an organic electrolytic solution is used in lithium batteries. The organic electrolytic solution is prepared by dissolving a lithium salt in an organic solvent. The organic solvent may be stable at high voltages and has high ionic conductivity, high permittivity, and low viscosity.
When a lithium battery uses a carbonate-based polar non-aqueous solvent, an irreversible reaction in which charges are excessively used due to a side reaction between carbon in an anode and an electrolytic solution occurs during initial charging. As a result of such an irreversible reaction, a passivation layer, such as a solid electrolyte interface (SEI) membrane, is formed on the surface of the anode. The SEI prevents decomposition of the electrolytic solution during charging and discharging and acts as an ion tunnel. The SEI passes only lithium ions therethrough during charging and discharging and blocks the organic solvent. Only the lithium ions are intercalated into the carbon anode, and the organic solvent is not intercalated with the lithium ions, and thus a breakdown of the anode structure is prevented. However, an excessive amount of charges is consumed in the formation of the SEI, and thus initial efficiency of the lithium battery is reduced. In addition, the SEI has a higher resistance than the anode itself, and thus cell capacity of the lithium battery is decreased. Therefore, when the SEI is formed, it is preferable that the decomposition of the electrolytic solution is minimized. For example, U.S. Pat. No. 5,352,548 discloses a method of preventing decomposition of a solvent adding a vinylene carbonate, or a derivative thereof, to an electrolytic solution, and then forming a film on a surface of a negative electrode through a reduction and decomposition reaction of the additive.